The aim of the study was to investigate the effects of high-dose medroxyprogesterone acetate (MPA) on the tumor necrosis factor-alpha (TNF-alpha) release in patients with chemotherapy-induced neutropenia. We also evaluated the effects of high-dose MPA on hematological parameters (leukocyte, neutrophil, platelet, hemoglobin, hematocrit) and side effects of MPA. One week following the first cycle chemotherapy, 20 patients who developed neutropenia were enrolled in the study. One gram/day MPA was administered orally to the patients and was continued from one week following the first chemotherapy cycle to one week after the second chemotherapy cycle. The patients received the second chemotherapy cycle at the same doses as the first cycle. Before MPA treatment TNF-alpha levels were lower than post-treatment levels, but the difference was not statistically significant (P>0.05). The differences in the mean leukocyte and neutrophil counts before and after the high-dose MPA treatment were statistically significant (p<0.05).